Gravity flow rack or order picking shelving systems in which merchandise cartons are placed at the rear of downwardly inclined shelves for sliding movement of the cartons toward the front of the shelves are well known in the art. The downwardly inclined shelves of such gravity flow rack systems generally comprise rectangular frames having roller track members and guide track members extending between front and rear shelf frame rails. A particularly commercially successful gravity flow rack system of the type being described is disclosed in, for example, U.S. Pat. No. 4,394,910 to Miller.
To date, many different structural connections have been developed for securing together the side and end rails for a shelf utilized in this type of shelving system. For example, U.S. Pat. No. 5,115,920 to Tipton et al. discloses in FIGS. 5, 14 and 15 a fastenerless structure for interconnecting the end and side rails of a shelf. The side rail includes a first longitudinal slot and a second, cooperating u-shaped slot that defines a resilient flap including an inwardly projecting leg. The end rail includes a hook that is received in the longitudinal slot. The connection of the end and side rails is made by inserting the hook into the longitudinal slot and then shifting the end rail downward relative to the side rail until the inwardly projecting leg of the resilient flap engages the upper surface of the bottom wall of the end rail.
While providing for positive engagement, this structure is relatively expensive to manufacture. It should also be appreciated that the inwardly projecting leg is often bent outwardly during assembly and, when this occurs it no longer provides the desired locking function. Further, when the desired locking function is provided significant difficulty is encountered when seeking to disengage the side and end rails and reconfigure the shelving system. In fact, the inwardly projecting leg is often damaged during disassembly thereby defeating the entire locking function, possibly even necessitating the purchase of a replacement siderail.
Of course, other possible joint structures for connecting the side and end rails of a shelf are also known. Examples of these include, for example, the structures disclosed in U.S. Pat. No. 3,510,010 to Gasner; U.S. Pat. No. 3,858,988 to Cohen and U.S. Pat. No. 3,881,829 to James. While each of these connecting structures provides the convenience of a fastenerless connection, they are all relatively expensive to produce, relatively easily damaged during installation and/or disassembly for subsequent reconfiguration or fail to provide the necessary security of connection for use in a shelving system of the type described.